Traffic. Mosquitoes. People who snap their gum. People who crack their knuckles. There are so many things in the world that are just downright annoying.

More content below this sponsor message

But what makes them annoying? It's the question that NPR Science Correspondent Joe Palca and Science Friday's Flora Lichtman set out to answer in their new book, Annoying: The Science of What Bugs Us.

For instance, why is hearing someone else's phone call more irritating than just overhearing a normal conversation? In an interview with Morning Edition's Renee Montagne, Lichtman explains why this is so grating.

"It's half of a conversation," she says. "Your brain goes into this mode where you start trying to predict what that person is going to say next. The thing that's frustrating about a cellphone conversation is that it's very hard to predict, which is one of the things that we found makes something annoying."

A study by a graduate student at Cornell University experimented with this idea of predicting speech by taking half of a conversation and garbling the words. Even though the test subjects couldn't understand half of what was being said, the annoying effects went away. "It's not just about the sound intruding your space," Lichtman says. "It seems to be about the speech itself."

Most people have something that particularly annoys them. For Lichtman, it's people who clip their nails on the subway in New York. That combination of someone else's hygiene habits and the sound of the clippers sets her teeth on edge.

Stay up-to-date with the latest news, stories and insider events.

Please enter a valid email addressOops, something went wrong!

You've signed up to receive emails. Please check your email for a welcome confirmation.

For Palca, the annoyance that tops his list is unexplained delays.

"You're in the airport and a flight is supposed to go at 10," he says. "At a quarter to 10, they haven't boarded the plane. And then at 10, they haven't boarded the plane. And at 10:15 they haven't boarded the plane, and nobody is telling you why."

There are, however, a few things out there that are universally annoying — like fingernails on a blackboard.

"It seems to be something intrinsic about that mix of frequencies," Lichtman says. "The change in volume rapidly — it's called 'rough' in acoustics — most people's ears don't like that stimulus."

While there are plenty of irritants in the world, there aren't a lot of ways to alleviate that sense of annoyance. Palca points out that they're part of human life, and they're something that everyone has to deal with from time to time.

But there are some techniques that people can use — for example, distracting yourself if you're stuck in a long line, or something Palca calls "cognitive restructuring."

"You can tell yourself that that mosquito is just a part of the life flow of the world and I shouldn't be mad," he says. "It's just trying to do what it was genetically programmed to do."

Basically, though, the bottom line is that you're stuck, it's annoying, and that's part of life.